Among photodiode arrays, there is known since priorly a front surface incidence type photodiode array, wherein output signals from the photodiode array are electrically connected to the back surface side by means of penetrating wirings (electrodes) that connect a light-incident surface side and a back surface side (see, for example, Japanese Published Unexamined Patent Application No. 2001-318155). As shown in FIG. 17, with the photodiode array disclosed in this publication, wirings 152 are formed on a front surface of the photodiode array 144 to take out signals from the respective diffusion layers 151 where the photodiodes 144a, 144b, 144c, . . . 144n, which are the main bodies of a photoelectric conversion unit, are formed, and each wiring 152 is extended so as to be connected to the penetrating wiring 154 that passes through from the front to the back of the Si substrate 153. Also at the back surface side of each photodiode 144 is formed the bump 155, connected to the penetrating wiring 154, and the intervals between the Si substrate 153 and the wirings 152 and the penetrating wirings 154 are insulated by the insulating films 156a, 156b, and 156c, which are silicon oxide films.